RESUMO
Objective Docetaxel is commonly used in chemotherapy for patients with mucoepidermoid carcinoma (MEC) in the salivary gland after operation,but it cannot kill all residual tumor cells and prevent recurrence.Cancer stem cells (CSCs) may be responsible for tumor recurrence and drug resistance.Based on the theory of CSCs,the authors investigated the effects of docetaxel on cancer stem cell-like cells in the MEC cell line MC3.Methods MC3 cells in the logarithmic growth phase were divided into a negative control and a docetaxel (40 ng/mL) group.The colony formation rate of the MC3 cells was calculated with the soft agar cloning technique,the growth of the cells detected by MTT assay,the protein and mRNA expressions of CD44 and Oct4 determined by immunocytochemistry and flow cytometry,and tumorigenicity observed by nude mouse tumorigenicity assay.Results Compared with the negative control group,the MC3 cells treated with docetaxel exhibited significant increases in the colony formation rate ([9.14±0.75] vs [33.47±1.30]％,P＜0.05),the protein expressions of CD44 (14.47±0.15 vs 99.50±0.30,P＜0.05) and Oct4 (1.37±0.06 vs 14.60±0.36,P＜0.05),and the mRNA expressions of CD44 (0.207±0.009 vs 0.651±0.015,P＜0.05) and Oct4 (0.223±0.008 vs 2.228±0.005,P＜0.05).At 2 months after injection of 1×103,1× 104,and 1×105 MC3 cells,tumor formation was observed in 0,1,and 3 of the nude mice,respectively,but not in the negative control group.Conclusion MC3 cells surviving docetaxel treatment have the properties of stem cells,and docetaxel can enrich cancer stem cells in the MC3 cells,which plays a key role in tumor recurrence.